Yes, the first "KVL" eq. has a sign error on V1. Perhaps because of a miss application of KVL as you do not have a closed continuous current loop with those elements. Anyway the KVL approach is overkill here. One of the advantages of op amps is their very high input impedances and low output impedances. So you can analyze the first amp in isolation from the second stage. So V1 and it's resistor and everything after it can be ignored to analyze the first stage. Then you do the second stage with the known Vo of the first stage.